Optical brighteners (herein OB) in polymers are known. The activity of a particular optical brightener depends on the polymer in which it is used. The combination of a particular polymer and a particular optical brightener must therefore go well with one another. The present invention provides new optical brighteners for polycarbonates and polyester carbonates.
WO 98/19862 discloses two-layer sheets made from polymers containing optical brighteners and UV absorbers in one of the two layers.
Hostalux® KCB is an optical brightener. Hostalux® KCB is 1,4-bis-(2-benzoxazolyl) naphthaline. It is available from Clariant GmbH, Frankfurt am Main, Germany. The use of Hostalux® KCB in TiO2-containing powder coatings is described in WO 01/18130.
The use of Hostalux® KCB in white pigment-containing printing papers is described in JP-A 2001-010210 and in JP-A 03-065948.
The use of Hostalux® KCB in combination with other optical brighteners in PVC or EVA is described in EP-A 0 791 680.
The use of Hostalux® KCB in combination with other optical brighteners in polyesters is described in EP-A 0 240 461 and in Helvetica Chimica Acta (1978), 61, pages 488 to 500.
The use of Hostalux® KCB in combination with other optical brighteners in polyesters and polyamides is described in EP-A 0 136 259 and in EP-A 0 044 996 and in DE-A 19 55 310.
The use of Hostalux® KCB in combination with other optical brighteners in PVC is described in DE-A 33 13 332.
The use of Hostalux® KCB in combination with other optical brighteners in textiles is described in DE-A 26 29 703.
The use of Hostalux® KCB in polyester films is described in DE-A 38 18 986.
The use of Hostalux® KCB in laminated PVC films is described in DE-A 21 33 16.0.
Leukopur® EGM is an optical brightener. Leukopur® EGM is 7-(2H-naphtho[1,2-d]triazol-2-yl)-3-phenyl-2H-1-benzopyran-2-one. It is available from Clariant GmbH, Frankfurt am Main, Germany. The use of Leukopur® EGM in “UV-detecting compositions” is described in JP-A 01-169327.
The use of Leukopur® EGM together with other optical brighteners in polyolefins is described in WO 02/31035.
The use of Leukopur® EGM together with other optical brighteners in PVC is described in DE-A 33 13 332.
The use of Leukopur® EGM in PVC is described in JP-A 040 46 348.
The use of Leukopur® EGM in polyester fibres is described in JP-A 02-033321 and in JP-A 570 56 516 and in JP-A 620 48 690.
The use of Leukopur® EGM in acrylic fibres is described in JP-A 011 92 816.
The use of Leukopur® EGM in greenhouse films is described in DE-A 38 18 986.
The use of Leukopur® EGM in polystyrene is described in U.S. Pat. No. 4,404,300.
Brochures published by the manufacturer of Hostalux® KCB and Leukopur® EGM (for example “Technical Information Hostalux® KCB” published by Clariant GmbH, Frankfurt am Main, Germany) mention a number of applications. Polycarbonate is not mentioned. PVC, PS, PE, PP, cellulose acetate and EVA are mentioned.
Hostalux® KSB is a known optical brightener for polycarbonate. Hostalux® KSB is 2-[4-[2-[4-(2-benzoxazolyl)phenyl]ethenyl]phenyl]-5-methyl benzoxazole. It is available from Clariant GmbH, Frankfurt am Main, Germany. The use of Hostalux® KSB in polycarbonate is described in JP-A 2002-003710 and in JP-A 2001-214049 and in JP-A 10-316873 and in DE-A 197 24 638.
Uvitex® OB is a known optical brightener for polycarbonate. Uvitex® OB is 2,2′-(2,5-thiophenediyl)bis[5-(1,1-dimethylethyl) benzoxazole. It is available from Ciba Spezialchemie, Lampertheim, Germany. The use of Uvitex® OB in polycarbonate is described in JP-A 2002-003710 and in JP-A 2000-191918 and in JP-A 072 33 314.
Polycarbonate and polyester carbonate are often used in products that are exposed to weathering. It is therefore important that plastics containing polycarbonate and polyester carbonate have good weathering resistance. The weathering resistance of plastics also depends on the additives (for example optical brighteners) that are used in the plastics.
The known optical brighteners for polycarbonate and for polyester carbonate have the disadvantage of not being adequately resistant to weathering.
The object of the present invention is therefore to provide optical brighteners for polycarbonate and for polyester carbonate that have good weathering resistance.